Ceramic ware towing device



P 1,1964 D. w. CROSHAW ETAL 3,146,552

CERAMIC WARE TOWING DEVICE Filed Feb. 6, 1962 United States Patent 3,146,552 CERAMIC WARE TOWING DEVICE Douglas Walter Croshaw, Arthur Dowley, Harold Roberts, and James Sidney Charles Patey, all of Stoke-on- Trent, England, assignors to Service (Engineers) Limited, Staifordshire, England, a British company Filed Feb. 6, 1962, Ser. No. 171,477 Claims priority, application Great Britain Feb. 14, 1961 5 Claims. (Cl. 5162) This invention is concerned with improvements in or relating to the towing of articles of ceramic ware.

Hitherto it has been customary in making an article of ceramic fiat-ware from moist clay for the article, after it has been shaped by forming tools and partially dried in an oven, to be towed by an operative who places it on a rotating support and smooths its upper surface by means of a piece of emery cloth, felt, or tow which he holds in his hand. Towing by hand in this way involves high labour costs, and the reliability of the operation is dependent on the skill of the operative. The term flatware is used herein, as is customary in the pottery industry, to denote plates and saucers as opposed to cups and bowls which are regarded as hollow-ware. There has been proposed, in United States patent specification No. 2,612,729, a machine for use in towing circular articles of ceramic flat-ware in the operation of which a device comprising a contoured strip of rubber or of similar flexible material split in the centre so as to allow each of the two halves of the strip to yield to the oppositely acting frictional effect on each side of the centre of rotation is presented to an upper surface of an article, the strip being diametrically disposed across the surface of the article while the article rotates about its central axis on a ware support. The contoured strip is faced with a material which will act as an abrasive, e.g. a material abrasive in itself, such as emery cloth, or a material which will pick up clay particles and acquire abrasive properties by using the particles as an abrasive agent, such as flannel.

It is one of the objects of the invention to provide an improved towing machine in which the towing device is presented to an article of ceramic ware to be operated on in such a manner that the article is brought to a uniformly smooth condition.

A machine of generally similar construction and arrangement to the machine described in the aforesaid specification No. 2,612,729 but comprising a towing device which, in the operation of the machine, presents to a rotating article a reciprocable contoured band of towing material progressively from the center portion of the article outwardly, is hereinafter described in greater detail as an illustrative embodiment of the invention. The towing material is mounted on a member supported in the machine and being so constructed that the overall outline at the work-engaging surface of the foam material, before coming into contact with the article, offers a contour complementary to the contour presented by a diametrical section through the article. The contoured strip of the towing device engages the article over little more than the length of a radius thereof, and while in engagement therewith a narrow contoured support of the towing device is reciprocated through a small amplitude normally to the axis of rotation of the article on which the device is operating, the amplitude of the reciprocations imparted to the support for the band of towing material being preferably of the order of /8 to of an inch. One complete reciprocation per second while the article is rotating at 450 revolutions per minute has been found satisfactory.

It has been found that, in using this towing machine, the contoured surfaces of flat-ware articles after drying of the clay but before firing, in the manufacture of ceramic ware, are brought to a uniformly smooth condition without un- V 3,146,552 Patented Sept. 1., 1964 ICE duly rubbing away those raised portions that form desirable parts of the designs of the articles and furthermore there is no apparent evidence of circular lines being scored on the surfaces of the articles.

The invention provides, as one of its several features, a machine for towing articles in the manufacture of ceramic ware comprising a rotatable work support, means for rotating the work support, a towing device movable towards and away from the Work support to bring the towing device into engagement with an article supported on the work support progressively from the center portion of the article outwardly, and means for moving the towing device as aforesaid, the towing device being reciprocable, while in engagement with the surface of the article, in the operation of the machine, through a small amplitude along a radius leading from the axis of rotation of the work support.

The invention further provides, as another of its several features, a method of towing articles in the manufacture of ceramic ware comprising the steps of rotating a work support, of presenting a towing device to the surface of an article of ceramic Ware supported on the work support progressively from the center portion of the surface outwardly, and of causing the towing device to reciprocate, while in engagement with the surface of the article, through a small amplitude along a radius leading from the axis of rotation of the work support.

The above and other features of the present invention will now be described in detail with reference to the accompanying drawing in which is represented a front view, largely in section, of an article support and towing device of the machine to be described.

The towing machine now to be described is similar in construction and arrangement to the machine described in the complete specification of United States Patent No. 2,612,729 and comprises a rotatable chuck 56 on resilient cushions 57 of which an operator places a circular article 59 of ceramic flat-ware (e.g. a plate) in a state of partial dryness which is reached when the water content is about 3% of the total weight of the article. At the centre of the chuck 56, which is supported above a table 68 forming part of the main frame (part of which is indicated at 64), a suction cup 58 is provided which is connected to a vacuum pump (not shown) through a passage 55 in a vertical shaft 54 on which the chuck 56 is supported for rotation, the suction cup 58 being arranged to hold in position an article 59 placed centrally on the chuck. The machine also comprises a towing device generally designated 32 (which takes the place of the main towing element of the machine described in the aforesaid specification) mounted on a vertically reciprocable rod 60 supported in a bracket 62 of the main frame 64 and positioned above the chuck 56. The vertical shaft 54, and consequently the chuck 56, is rotated in any convenient manner (e.g. by means of an electric motor) and the rod 60 is moved towards and away from the chuck 56, also in any convenient manner (e.g. by a linkage system such as is partly shown and described in the aforementioned specification), to bring the towing device 32 into engagement with an upper surface of an article 59 supported on the chuck 56 while the chuck is rotated. The towing device 32 of the machine comprises a slide 30 carried at the lower end of the vertically reciprocable rod 60 and urged to the left (as viewed in the drawing) by a spring 33, as will be referred to later. A link 34 pivoted to the slide at 36 is connected by a pivot pin 38 to a boss 39 on a support 40 of the towing device 32 of the machine, a pin 37 being provided on the slide 30 to restrict anticlockwise movement of the link 34 about the pivot 36. The support 40, which extends a little over the length of a radius of the chuck 56, has an under-surface of a contour complementary to the contour presented by a diametrical section through an article to be operated on. Spring clips 42 secured to the support 40 clip over a flexible metal sheet 44 to which is stuck a strip 46, or a number of separate pieces, of towing material. A polyurethane foam material in which abrasive grains are embedded has been found to be a particularly satisfactory towing material. The towing device further comprises a compression spring 48 acting between the bottom of the rod 60 and the top of the support 40 positioned above the centre of the chuck 56 and a second compression spring 50 secured at its upper end to the slide 30 and arranged to be engaged at its lower end by the portion of the top of the support 40 positioned above the periphery of the chuck 56. Mounted in the frame 64 and supported by a bush 66 secured in the table 68 is a shaft 70 conveniently driven by an electric motor (not shown). Mounted eccentrically at the upper end of the shaft 70 is a roll 72 against which a roller 74 mounted in the slide 36 abuts, the spring 33 being provided in the slide 30 constantly to urge the roller 74 into engagement with the roll 72. The upper end of the shaft 70 is threaded to receive a nut 76 by means of which the roll 72 may be locked in any desired position thereon. A polyurethane foam material for the towing device 32 may be conveniently formed from a mixture formulated as follows:

Parts by weight Daltocel DA 5 Suprasec DA 3 Grit 5 Daltocel DA and Suprasec DA are reactive components for making a flexible polyurethane foam obtainable from Imperial Chemical Industries Limited. The grit is emery, ground talc or aluminum oxide of 320 to 220 British standard specification grain size. The work-engaging surface of the towing device 32 may be in the form of a strip of uniform thickness (as shown in the drawing) of polyurethane foam material with fine abrasive grains embedded therein, or alternatively, may be formed by a number of separate pieces of the said material, conveniently of /1 inch cross section, stuck on to the flexible element 44 mounted on the under-surface of the support 40, said pieces being substantially parallel to each other but inclined to the length of the support 40 so as to overlap one another when viewed from one side. The foam material, being in each case of uniform thickness, thus presents an overall outline at the work-engaging surface of the towing device 32 contoured complementarily to the contour presented by a diametrical section through the article 59.

In the operation of the machine, an article 59 is placed centrally on the chuck 56 which is rotated as aforesaid; the article is securely gripped thereon by the action of the suction cup 58, arms (not shown, but described in the aforementioned specification) being arranged to insure that the article is centrally disposed on the chuck. The springs 48, 50, of which the spring 48 is the more powerful, are effective, when the towing device 32 is in an inoperative position, to urge the link 34 anti-clockwise about its pivot 36 until it abuts against the pin 37 and further to urge the portion of the support 40 positioned above the centre of the chuck 56 nearer to the chuck than the portion of the support positioned above the periphery thereof (as shown in the drawing). Thus the springs 48, 50 insure that the article 59 to be operated on is engaged firstly at its centre as the towing device is moved into engagement therewith while further movement of the towing device, in the operation of the machine, is effective, through the springs 48, 50, resiliently to urge the whole of the work-engaging portion of the towing device into engagement with the surface of the article and, through the link 34, to cause the support 40 to move outwardly from the axis of rotation of the chuck 56. In this way the strip 46 of towing material is able to bed into any sharply contoured root that may be found on the upper surface of the article 59.

Conveniently the slide 30 is arranged to be recipro cated continuously while the machine is in use. Thus the shaft 70 is rotated continuously while the machine is in use and the roll 72, into engagement with which the roller '74 on the slide 30 is urged constantly by the spring 33, is so constructed and arranged as to embrace extreme positions of the roller 74 corresponding to the operative and inoperative positions of the towing device. The roll 72 is further provided with a bore 73 which passes through the centre of the roll and is arranged to receive the upper end portion of the shaft 70, a collar 75 on the shaft acting as a support for the roll. The bore 73 facilitates the adjustment of the position of the roll 72 relative to the shaft whereby to vary the eccentric mounting of the roll, the nut 76 being provided to lock the roll, in its adjusted position, against the collar 75, and in this way the throw of the roll is varied and, together therewith, the amplitude of the reciprocations of the slide 30. Amplitudes of the order of A; to of an inch have been found to be satisfactory. Reciprocating the slide 30 at the rate of one complete reciprocation per second, e.g. by means of an electric motor (not shown) operating at a speed of 60 revolutions per minute, when the chuck 56 is rotating at 450 revolutions per minute, has also been found satisfactory.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. In a machine for towing articles in the manufacture of ceramic ware, a rotatable support for a generally circular article having a contoured surface to be towed, a towing device having an elongated towing surface extending radially outward from the axis of rotation of the support, said surface being substantially complementary to the contour of the surface of the article along a radius thereof, means for moving the device bodily into and out of engagement with the article surface, means mounting the device on the moving means for additional movement radially with respect to the axis of rotation of the support, and means for moving the device outwardly from said axis upon engagement with said surface for causing the device to be engaged fully in the contours of said surface.

2. In a machine for towing articles in the manufacture of ceramic ware, a rotatable support for a generally circular article having a contoured surface to be towed, a towing device having an elongated towing surface extending radially outward from the axis of rotation of the support, said towing surface being substantially complementary to the contour of the surface of the article along a radius thereof, means for moving the device bodily into and out of engagement with the article surface, means mounting the device on the moving means for yielding movement upon engagement with the article surface, said towing surface when out of engagement with the article surface being disposed by the mounting means at an angle declining toward the axis of rotation of the article surface whereby engagement between the towing surface and the article surface occurs progressively from the axis outwardly as the device yields during its bodily movement.

3. In a machine for towing articles in the manufacture of ceramic ware, a rotatable support for a generally circular article having a contoured surface to be towed, a towing device having an elongated towing surface extending radially outward from the axis of rotation of the support, said towing surface being substantially complementary to the contour of the surface of the article along a radius thereof, means for moving the device bodily into and out of engagement with the article surface, means mounting the device on the moving means for yielding movement upon engagement with the article surface, said towing surface when out of engagement with the article surface being disposed by the mounting means at an angle declining toward the axis of rotation of the article surface whereby engagement between the towing surface and the article surface occurs progressively from the axis outwardly as the device yields during its bodily movement, said mounting means including a pivoted member for causing the device during its yielding movement to be moved radially outward from the axis of rotation of said article on the support for causing the device to be seated firmly in the contours of said article surface.

4. In a machine for towing articles in the manufacture of ceramic ware, a rotatable support for a generally circular article having a contoured surface to be towed, a towing device having a work-engaging portion of resilient foam material with abrasive grains embedded therein, said portion having a contour substantially complementary to the contour of the surface of the article along a radius thereof, means for moving the device bodily into and out of engagement with the article surface, means mounting the device on the moving means for additional movement radially with respect to the axis of rotation of the support, and means for moving the device outwardly away from said axis upon engagement with said surface for causing said resilient portion to be seated firmly against the contours of said surface.

5. In a machine for towing articles of ceramic ware, a rotatable support for a generally circular article having a contoured surface to be towed, a towing device having an elongated towing surface extending radially outward from the axis of rotation of the support, said surface being substantially complementary to the contour of the surface of the article along a radius thereof, a slide reciprocable normally to the axis of rotation of the support, means carrying the slide for bodily movement toward and away from the support, means mounting the device on the slide for yielding movement upon engagement with the article surface during bodily movement of the slide toward the support, said mounting means including a pivoted member for causing the device during its yielding movement to be moved radially outward from the axis of rotation of the article on the support for causing the device to be seated firmly in the contours of said article surface, and means for reciprocating the slide whereby a reciprocating motion is imparted to said device as the article surface is being towed.

References Cited in the file of this patent UNITED STATES PATENTS 2,324,410 Miller July 13, 1943 2,612,729 Walley et al. Oct. 7, 1952 2,804,728 Politzer Sept. 3, 1957 2,996,850 Hoffman Aug. 22, 1961 FOREIGN PATENTS 26,918 Netherlands Ian. 16, 1933 756,341 Great Britain Sept. 5, 1956 

1. IN A MACHINE FOR TOWING ARTICLES IN THE MANUFACTURE OF CERAMIC WARE, A ROTATABLE SUPPORT FOR A GENERALLY CIRCULAR ARTICLE HAVING A CONTOURED SURFACE TO BE TOWED, A TOWING DEVICE HAVING AN ELONGATED TOWING SURFACE EXTENDING RADIALLY OUTWARD FROM THE AXIS OF ROTATION OF THE SUPPORT, SAID SURFACE BEING SUBSTANTIALLY COMPLEMENTARY TO THE CONTOUR OF THE SURFACE OF THE ARTICLE ALONG A RADIUS THEREOF, MEANS FOR MOVING THE DEVICE BODILY INTO AND OUT OF ENGAGEMENT WITH THE ARTICLE SURFACE, MEANS MOUNTING THE DEVICE ON THE MOVING MEANS FOR ADDITIONAL MOVEMENT RADIALLY WITH RESPECT TO THE AXIS OF ROTATION OF THE SUPPORT, AND MEANS FOR MOVING THE DEVICE OUTWARDLY FROM SAID AXIS UPON ENGAGEMENT WITH SAID SURFACE FOR CAUSING THE DEVICE TO BE ENGAGED FULLY IN THE CONTOURS OF SAID SURFACE. 